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JIT/Lean ProductionJIT/Lean Production
Just-in-time (JIT): A highly coordinated processing system in which goods move through the system, and services are performed, just as they are needed,
JIT lean production
JIT pull (demand) system
JIT operates with very little “fat”
Goal of JITGoal of JIT
The ultimate goal of JIT is a balanced system.
Achieves a smooth, rapid flow of materials through the system
Summary JIT Goals and Building Summary JIT Goals and Building BlocksBlocks
Figure 14.1
Product Design
ProcessDesign
PersonnelElements
Manufactur-ing Planning
Eliminate disruptions
Make the system flexible Eliminate waste
Abalancedrapid flow
UltimateGoal
SupportingGoals
BuildingBlocks
Supporting GoalsSupporting Goals
Eliminate disruptions
Make system flexible
Eliminate waste, especially excess inventory
Sources of WasteSources of Waste
Overproduction Waiting time Unnecessary transportation Processing waste Inefficient work methods Product defects
Big JIT – broad focus Vendor relations Human relations Technology management Materials and inventory management
Little JIT – narrow focus Scheduling materials Scheduling services of production
Big vs. Little JITBig vs. Little JIT
JIT Building BlocksJIT Building Blocks
Product design Process design Personnel/organizational
elements Manufacturing
planning and control
Product DesignProduct Design
Standard parts
Modular design
Highly capable production systems
Concurrentengineering
Process DesignProcess Design
Small lot sizes
Setup time reduction
Limited work in process
Quality improvement
Production flexibility
Little inventory storage
Benefits of Small Lot SizesBenefits of Small Lot Sizes
Reduces inventory
Less storage space
Less rework
Problems are more apparent
Increases product flexibility
Easier to balance operations
Production FlexibilityProduction Flexibility
Reduce downtime by reducing changeover time
Use preventive maintenance to reduce breakdowns
Cross-train workers to help clear bottlenecks
Production Flexibility (cont’d)Production Flexibility (cont’d)
Use many small units of capacity Reserve capacity for important customers
Quality ImprovementQuality Improvement
Autonomation
Automatic detection of defects during production
Jidoka
Japanese term for autonomation
Personnel/Organizational ElementsPersonnel/Organizational Elements
Workers as assets
Cross-trained workers
Continuous improvement
Cost accounting
Leadership
Manufacturing Planning and ControlManufacturing Planning and Control
Level loading
Pull systems
Visual systems
Close vendor relationships
Reduced transaction processing
Preventive maintenance
Pull/Push SystemsPull/Push Systems
Pull system: System for moving work where a workstation pulls output from the preceding station as needed. (e.g. Kanban)
Push system: System for moving work where output is pushed to the next station as it is completed
Kanban Production Control SystemKanban Production Control System
Kanban: Card or other device that communicates demand for work or materials from the preceding station
Kanban is the Japanese word meaning “signal” or “visible record”
Paperless production control system
Authority to pull, or produce comes from a downstream process.
Kanban FormulaKanban Formula
N = DT(1+X)C
N = Total number of containers
D = Planned usage rate of using work center
T = Average waiting time plus average production time for a container of parts
X = Policy variable set by management - possible inefficiency in the system
C = Capacity of a standard container
Traditional Supplier NetworkTraditional Supplier Network
BuyerBuyer
SupplierSupplierSupplierSupplier SupplierSupplier SupplierSupplier
SupplierSupplier
SupplierSupplierSupplierSupplier
Figure 14.4a
Tiered Supplier NetworkTiered Supplier NetworkFigure 14.4b
SupplierSupplier
SupplierSupplier
SupplierSupplier
SupplierSupplierSupplierSupplier SupplierSupplier
BuyerBuyer
SupplierSupplierFirst Tier SupplierFirst Tier Supplier
Second Tier SupplierSecond Tier Supplier
Third Tier SupplierThird Tier Supplier
Comparison of JIT and TraditionalComparison of JIT and Traditional
Factor Traditional JIT
Inventory Much to offset forecast errors, late deliveries
Minimal necessary to operate
Deliveries Large Small
Lot sizes Large Small
Setup; runs Few, long runs Many, short runs
Vendors Long-term relationships are unusual
Partners
Workers Necessary to do the work
Assets
Table 14.3
Transitioning to a JIT SystemTransitioning to a JIT System
Get top management commitment
Decide which parts need most effort
Obtain support of workers
Start by trying to reduce setup times
Gradually convert operations
Convert suppliers to JIT
Prepare for obstacles
Obstacles to ConversionObstacles to Conversion
Management may not be committed
Workers/management may not be cooperative
Suppliers may resist
JIT in ServicesJIT in Services
The basic goal of the demand flow technology in the service organization is to provide optimum response to the customer with the highest quality service and lowest possible cost. Eliminate disruptions Make system flexible Reduce setup and lead times Eliminate waste Minimize WIP Simplify the process
JIT II: a supplier representative works right in the company’s plant, making sure there is an appropriate supply on hand.
JIT IIJIT II
Benefits of JIT SystemsBenefits of JIT Systems
Reduced inventory levels
High quality
Flexibility
Reduced lead times
Increased productivity
Benefits of JIT Systems (cont’d)Benefits of JIT Systems (cont’d)
Increased equipment utilization
Reduced scrap and rework
Reduced space requirements
Pressure for good vendor relationships
Reduced need for indirect labor
Smooth flow of work (the ultimate goal) Elimination of waste Continuous improvement Eliminating anything that does not add
value Simple systems that are easy to manage Use of product layouts to minimize moving
materials and parts Quality at the source
Elements of JITElements of JIT